Alt-BEAM Archive

Message #03090



To: beam@corp.sgi.com
From: Wouter Brok w.j.m.brok@stud.tue.nl
Date: Sat, 08 May 1999 20:07:47 +0200
Subject: [alt-beam] non-block-wave signal for steppermotor


Hello,

just an idea I was thinking about:

In general stepper motors are driven with block-form waveforms at the
inputs. I don't think this is favorable from the energetic point of view;
what I mean is this: When one input of a bipolar stepper-motor is made high
(suppose this is the driving voltage level, so all the others are low) the
motor-axis will turn in the appropriate direction because it is attracted
by the powered coil. At a certain point however the axis is at the position
from where on the powered coil will slow the axis down. At that point the
input which was high should be made low and the next input should be made
high as to power the next coil so that the axis is attracted to the next
position. However, I do think it doesn't happen this way generally: the
input will be made low just to late, so the motor-axis will be slowed down.
This results in a waste of energy.
My thought was to feed the steppermotor with another waveform to increase
its efficiency, but what is this waveform? another possibility that came up
thinking about it is: the motor will add an induction-voltage on top of the
driving voltage and maybe this signal can be used to make an addaptive
motor-driving-circuit. The motordriver could 'decide' from some
characteristic of the induction-voltage if the driving signal should be
altered: feedback; the driving circuit can create the best waveform itself.
My guess is that this will result in a more efficient steppermotor-motion
and that the angular velocity of the motor can be higher as possible with a
normal block-wave; the motor will work more smoothly.

Any comments on this thought?

Wouter Brok.



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